By the turn of the twentieth century, the American search for new frontiers led not West but toward a golden age of technology. The invention of the telephone, the electric light bulb, the airplane, and numerous other achievements of science and engineering inspired a faith that technology would always improve the human condition. This same confidence would fuel the drive for "better living through chemistry" that produced chlorofluorocarbons - or CFCs. Spanning six decades, the story of CFCs vividly portrays the unintended consequences of technological progress and the ongoing struggle to contain the threat to the global environment. The invention of chlorofluorocarbons in 1928 by General Motors scientist Thomas Midgley, Jr., was celebrated as a boon to humanity: CFCs made possible both the mass proliferation of air conditioning and refrigeration. By the 1950s CFCs had found further applications: as propellants in aerosol spray cans, in the manufacture of Styrofoam, and as vital industrial solvents. Then, in 1974, after millions of tons of CFCs had been released into the Earth's atmosphere, two scientists at the University of California demonstrated that these same "safe" wonder substances had altered the fundamental chemistry of the atmosphere and had begun to erode the ozone layer - the protective shield of all life on earth. The battle to restrict CFCs was fought in laboratories, at international conferences, and in the halls of Congress, pitting environmentalists intent on remedying what had become a global crisis against industrialists and government officials opposed to regulation. Finally, in 1987, fifty-seven nations signed the first global environmental treaty - the Montreal Protocol, which regulated the further production of CFCs and ushered in a new era of international cooperation on the environment. In chronicling the rise and fall of one of the first synthetic chemicals, Cagin and Dray recreate the excitement of the age of invention that spawned CFCs, chart the growth of the environmental movement and the vital laws its activists succeeded in passing, and trace our dawning awareness of the fragility of the global environment. A richly detailed work of social and scientific history, Between Earth and Sky is ultimately the story of how we have come to understand the high cost of progress.